The Northwestern University Transgenic and Targeted Mutagenesis Laboratory (TTML) is a shared resource designed to produce genetically engineered mice for research projects of investigators ofthe Robert H Lurie Comprehensive Cancer Center (RHLCCC), Feinberg School of Medicine (FSM), Evanston campus, and Lurie Children's Hospital of Chicago Research Center. The transgenic facility was initially founded at Northwestern University in 1989, as part ofthe Markey Program in Developmental Biology, to provide a resource for generating transgenic mice. Today, the facility has evolved into a well utilized laboratory that provides a broad range of services to NU investigators, including generation of transgenic mice, gene targeting of embryonic stem (ES) cells, generation of chimeric mice via ES cell microinjection into blastocysts, cryopreservation and recovery of mouse embryos/sperm, and rederivation of pathogen free mouse strains. In 2003, the facility was reorganized and expanded to include gene targeting services. Embryo cryopreservation and recovery, rederivation of mouse lines, and in vitro fertilization services were added in 2005. The embryo, and now sperm, cryopreservation and recovery services position NU and Cancer Center investigators to capitalize on emerging repositories of mutant mice generated around the world, most of which are stored as cryopreserved embryos. Innovative genome editing technologies have been introduced over the last 18 months. These technologies implore zinc finger nuclease (ZFN) and recombinase mediated cassette exchange (RMCE) mechanisms to create gene-specific modifications directly in the zygote via pronuclear microinjection. Cancer Center investigators save both monetary resources and time as these technologies eliminate the need for ES cell based gene targeting. The TTML provides the necessary infrastructure that allows most investigators access to transgenic technology that normally requires expensive microinjection equipment and highly skilled staff with expertise in microinjection, microsurgeries, embryo manipulation, animal husbandry, and ES cell culture. TTML staff provides consultation and guidance regarding transgenic and targeting vector design; appropriate screening strategies; DNA purification methods; breeding and analysis of transgenic founder and chimeric mice; and transgenic-related technologies. The oversight committee that governs the TTML meets at least twice a year and is comprised of a dynamic group of faculty with a wide range of transgenic-related expertise. They critically review facility data/progress and provide astute advice. Since the inclusion ofthe TTML as a resource within the Cancer Center in 1995, Cancer Center investigators have consistently been the primary group of NU investigators utilizing the TTML, emphasizing its pivotal role in the overall research mission ofthe RHLCCC.